Acid retardation

Retarders were originally arenecarboxylic acids. These acidic materials not only delay the onset of cross-linking but also slow the cross-linking reaction itself. The acidic retarders do not function weU in black-fiUed compounds because of the high pH of furnace blacks. Another type of retarder, A/-nitroso diphenylamine [86-30-6] was used for many years in black-fiUed compounds. This product disappeared when it was recognized that it trans-nitrosated volatile amines to give a several-fold increase in airborne nitrosamines. U.S. production peaked in 1974 at about 1.6 million kg. 

Chemical Designations - Synonyms o-Hydroxybenzoic acid Retarder W Chemical Formula 1,2-HOCsHiCOOH. 

Ingold et al. ° showed that nitrous acid retards both zeroth- and first-order... 

This mechanism is supported by these facts (1) the kinetics are second order (first order in each reactant) (2) added acetic acid retards the reaction (drives the equilibrium to the left) and (3) cis glycols react much more rapidly than trans glycols. For periodic acid the mechanism is similar, with the intermediate ... 

Typical non-enolising aldehydes are formaldehyde and benzaldehyde, which are oxidised by Co(III) Ce(IV) perchlorate and sulphate , and Mn(III) . The main kinetic features and the primary kinetic isotope effects are the same as for the analogous cyclohexanol oxidations (section 4.3.5) and it is highly probable that the same general mechanism operates. kif olko20 for Co(III) oxidation of formaldehyde is 1.81 (ref. 141), a value in agreement with the observed acid-retardation, i.e. not in accordance with abstraction of a hydroxylic hydrogen atom from H2C(OH)2-The V(V) perchlorate oxidations of formaldehyde and chloral hydrate display an unusual rate expression, viz. 

Pronounced acid-retardation occurs at acidities lower than 10" The reac-... 

Water accelerates this reaction and acids retard it. The study of the reaction of peracid with S02 by stop-flow technique [40] showed the following empirical equation for the reaction rate ... 

Organic acids retard the formation of nitroxyl radicals via the reaction of the peroxyl radical with the aminyl radical [10], Apparently, the formation of a hydrogen bond of the >N H0C(0)R type leads to the shielding of nitrogen, which precludes the addition of dioxygen to it, yielding the nitroxyl radical. Thus, the products of the oxidation of alcohols, namely, acids have an influence on the mechanism of the cyclic chain termination. 

One of the reasons that it took so long for the acid retardation process to become... 

There is indeed a striking similarity between the salt separation processes discussed here and the acid retardation process. Consequently, it was possible to use the same basic process flow-sheet and equipment for these salt purification processes that have been extensively used for over 20 years for APU systems. 

It is pertinent to observe here that the following inorganic acids almost exhibit equal strength in aqueous solutions, whereas in non-aqueous solvents, their acidity retards in the following order ... 

Synonyms AI3-03710 Benzenecarboxylic acid Benzeneformic acid Benzenemethanoic acid Benzoate BRN 0636131 Carboxybenzene Caswell No. 081 CCRIS 1893 Dracylic acid E 210 EINECS 200 618-2 EPA pesticide chemical code 009101 Flowers of benjamin HA 1 NA 9094 NSC 149 Phenylcarboxylic acid Phenylformic acid Retarder BA Retardex Salvo liquid Salvo powder Tennplas UN 9094 Unisept BZA. 

Against a white surface this colour reaction may be observed even with a 0-00001 per cent, concentration of selenious acid. The reaction is more sensitive with sulphuric acid above 75 per cent, concentration than with dilute acid. The test is not applicable if the sulphuric acid contains iron. Tellurous acid retards the reaction.1... 

A slow-burning BkPdr suitable for fuses is obtained by incorporating ca 0.5% of high-viscosity oil, such as castor oil) J)C.W. Brooks,CanP 348641(1935) CA 29,3518(1935) (Addn of 0.1-0.5% of stearic acid retards the rate of burning eg, NaNOa 72.0, S 10.0, charcoal 17.7 stearic acid 0.3%) K)C.W.Brooks, Jr,USP 2030096(1936) CA 30,2388(1936) (Stability of BkPdrs contg AN is improved by incorporating 0.2% or more of a solid org basic compd such as urea of dicyandiamide)... 

Role of Ascorbates At low levels 100 ppm) ascorbic acid has been shown to catalyze development of WOF as shown by increased TBA values 0> 3). At higher levels (>1,000 ppm), however, ascorbic acid retards oxidation (3). Although the mechanism of retardation is not known, it Was been suggested that high levels of ascorbates may upset the balance between... 

Urea (carbamide, carbonyl diamide, CAS no 57-13-6, molecular weight 60.08) is a white, crystalline, and quite inexpensive powder. The substance is hygroscopic, freely soluble in water, slightly soluble in alcohol, and practically insoluble in ether.15 It is readily incorporated in topical formulations by virtue of its solubility. However, urea in solution hydrolyzes slowly to ammonia and carbon dioxide.15 In one patent it is claimed that lactic acid retards the decomposition of urea.16 Unstable preparations may need to be stored in a refrigerator.15... 

Hyaluronan hinders the onset of differentiation, as discussed earlier. Retinoic acid retards the differentiation of epidermal keratinocytes, as shown in skin organ cultures, a result of the ability of retinoic acid to stimulate HA deposition.263-265 Retinoic acid leads to the accumulation of HA in the superficial layers of the epidermis by stimulating HA synthesis specifically in keratinocytes. Some of this accumulation occurs as expanded intercellular HA, which may account for the weakened cohesion of keratinocytes observed both in vivo and in vitro. 

In alkaline solution oxidation of ferrous iron is fairly rapid,8 but certain acids retard the reaction. Ferrous sulphate, for example, in the presence of free sulphuric acid, is very stable in air. Concentrated hydrochloric acid assists the oxidation, as also do traces of certain substances, such as platinic and cupric chlorides, palladium nitrate, etc.9... 

Conjunct polymerization should be kept to a minimum, as it represents a loss of olefin and acid. Retardation of conjunct polymerization is favored by a low temperature, as in alkylation, especially in that portion of the absorber with the strongest... 

KYSELINA BENZOOVA (CZECH) PHENYL CARBOXYLIC ACID PHENYLFORMIC ACID RETARDER BA RETARDEX SALVO LIQUID SALVO POWDER TENN-PLAS... 

SYNS ACIDO SALICIUCO (ITALIAN) o-HYDROXY-BENZOIC ACID 2-HYDROXYBENZOIC ACID KERALYT ORTHOHYDROXYBENZOIC ACID RETARDER W D SA SAX... 

The retardation of decomposition of certain endothermic substances (oxygenated water, nitrous acid), retardation ceasing by the introduction of gaseous bubbles or of porous substances containing gas ... 

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